Oil pressure?

I found 2 TSB's that mey be relevant to your question?

7.3L DIESEL DI - HIGH PRESSURE OIL PUMP LEAK
TECHNICAL SERVICE BULLETIN
Reference Number(s): 04-4-4, Date of Issue: March 8, 2004
FORD:1998-2003 E SERIES; 1999-2003 SUPER DUTY F SERIES; 2000-2003 EXCURSION, F-650, F-750
Superceded Bulletin(s): 03-21-50, Date of Issue: October 7, 2003, 03-17-1, Date of Issue: September 1, 2003
Related Ref Number(s): 03-17-1, 03-21-50, 04-4-4
ARTICLE BEGINNING
DESCRIPTION
NOTE:This article supersedes TSB 03-21-50 to update the service procedure and illustration.

ENGINE - 7.3L DIESEL DI - HIGH PRESSURE OIL PUMP LEAK
ISSUE
Some 1998-2003 E-Series, 1999-2003 Super Duty, 2000-2003 Excursion, and 2000-2003 F650/750 vehicles equipped with a 7.3L Diesel engine may exhibit an oil leak at the high pressure oil pump outlet fittings and/or end plug (see Fig. 1 ). The leak may appear to be a rear main crankshaft seal, oil pan gasket, or other engine oil leak due to the drain hole machined in the crankcase valley which allows any oil in the valley to run down the back of the engine.
ACTION
High pressure oil pump leaks at the outlet fittings and/or end plug can be serviced without removing the pump assembly. Replace the O-rings on the fittings and the end plug using Kit 2C3Z-9G804-AA. All three (3) O-rings should be replaced. Apply liquid thread sealer (included in the kit) prior to reinstallation. Refer to the following Service Procedure for details.

ENGINE OIL LEVEL INDICATOR MARKINGS - REPORTS OF LOW OIL LEVEL
TECHNICAL SERVICE BULLETIN
Reference Number(s): 03-8-3, Date of Issue: April 28, 2003
FORD:2002 ESCORT; 2002-2003 CROWN VICTORIA, ESCORT ZX2, FOCUS, MUSTANG, TAURUS, THUNDERBIRD, E SERIES, ESCAPE, EXCURSION, EXPEDITION, EXPLORER SPORT TRAC, EXPLORER SPORT, EXPLORER, F-150, RANGER, SUPER DUTY F SERIES, WINDSTAR
LINCOLN:2002 CONTINENTAL; 2002-2003 LS, TOWN CAR NAVIGATOR; 2003 AVIATOR
MERCURY:2002-2003 COUGAR, GRAND MARQUIS, SABLE; 2002 VILLAGER; 2002-2003 MOUNTAINEER

Related Ref Number(s): 03-8-3
ARTICLE BEGINNING
DESCRIPTION
ENGINE - ENGINE OIL LEVEL INDICATOR MARKINGS - REPORTS OF LOW OIL LEVELS
ISSUE
Reports from the field indicate incorrect or low engine oil levels are being found at Pre-Delivery Inspection on new vehicles received in dealer inventory. In most cases, the level is being misinterpreted because the fluid fill mark on the stick is not touching the top hash mark at the upper limit (or MAX mark), or is partway down the crosshatch area.
ACTION
Ford is in the process of standardizing the markings across all vehicle lines. Current markings shown will be upgraded to a refined marking, shown in Fig. 1. Both markings will be used in production over the next few years. Oil levels will still be recorded in the crosshatched area of the blade, between the upper and lower limit holes. Vehicles shipped with engine oil levels falling within this area are acceptable and do not require topping off. Oil fill quantities are precisely measured at the plants and account for slight variations that may occur in oil pan volumes, indicator length, and pressed-in locations of the indicator tube into the block. For customer use, the markings continue to serve as a guide to refilling the engine to the correct initial fill volume with filter or, to top off the engine when it is determined the level is below the lower hole.
SERVICE INFORMATION
Ensure the vehicle is sitting on level ground. Set the park brake and ensure the transmission selector lever is in PARK position, or in FIRST gear on manuals. The engine must be OFF.
The best time for determining oil level is before the engine is started and the oil has had sufficient drainback time to the sump. If the engine has been running, allow it to sit for a few minutes turned off. An oil drainback period is required before taking an initial reading.
If the level falls below the lower hole, fill with one quart of oil. If one quart is insufficient to raise the level above the mark, add oil until it records within the crosshatch area. Use caution during this procedure as some time is needed for oil to drain down through the drainback passages in the cylinder head, to the oil pan. Adding oil a quart at a time repeatedly without sufficient drainback may overfill the sump.
If the oil level falls between the upper and lower hole do not add more oil. Adding an extra quart could cause overfilling and may result in aeration (foaming) causing eventual damage to vital bearing surfaces and moving parts inside. Overfilling will require some oil to be drained out until the indicator shows the level between the upper and lower holes of the blade. DO NOT expect the engine to "consume" the extra oil back down to the upper oil fill level hole, or consider it as extra lubrication protection for the engine.

Low oil pressure:

Check the oil pressure with a mechanical gauge, if normal replace the oil pressure switch. If abnormal could mean oil pump and engine bearing.

A deep hollow knock maybe a bearing problem due to low oil pressure. Get the oil pressure tested with a mechanical gauge. Please post the readings cold idle, hot idle and hot 1500 rpm here for further assistance.